if not then is the product working as advertised? - you already said yes

did you have a chance to examine the goods before hand? - well i guess not but you chose to buy off an online site

for any of the above you would have the right to be refunded in full.

However you also have the right to refund the product anyway under the cooling off period, however they have the right to charge you a reasonable fee as you did open the packaging and use the product. what they deem reasonable is up to them.

No, you're not entitled to a refund unless the product you bought is defective, is not fit for purpose or was sold to you through direct marketing. It's legislation to protect the consumer, not some catch-it-all money back guarantee...

You willingly bought the thing; they're under no obligation to take it back. They might, as a gesture of good faith, but they'll invariably (and reasonably) expect you to pay for usage/shipping/repackaging/restocking if they do accept your return.